Treatment of polyolefin-fatty acid salt mixtures with a hydrocarbon or halogenated hydrocarbon to improve dye receptivity



United States Patent 6502222 US. Cl. 260-23 Int. Cl. D06m 7/00; C081 29/02 6 Claims ABSTRACT OF THE DISCLOSURE This specification discloses an improvement in the method of dyeing polyolefins in which a metal-containing compound, such as a fatty acid salt, is present in the polyolefin composition to provide dyesites and in which the dyeing is carried out with dyes or coloring agents which, in addition to the coloring groups, have a hydroxyl group which is present in an ortho position with respect to a carbonyl group. The improvement in dyeability is provided by a pretreatment of the metal-containing polyolefin composition, prior to the dyeing steps; the pretreatment consists of contact with an organic solvent in which the maximum solubility of the polyolefin is by weight and the maximum swelling is 15% by volume. Solvents of the type used in dry cleaning are suitable.

This invention relates to a process for improving the dyeability of a polyolefin. More particularly, the invention relates to a method of treating a polymer of an alpha monoolefin and especially polypropylene in order to improve its dyeability.

The difficulty of dyeing or otherwise coloring polymers of alphamonoolefins is well known. Untreated polyolefins have at best very slight dyeability which is wholly unacceptable. Considerable effort throughout the industry has been given in attempting to improve the dyeability of these polymers and fabrics prepared therefrom. One important method has been to incorporate into the polymer a small amount of a metal compound, said metal having a valence of at least two and especially metal salts of the higher fatty acids and dyeing the metal-containing polymer with a coloring agent having in addition to its coloring group a hydroxyl group in an ortho position to a carbonyl group.

It has been found according to this invention that if a metal containing polyolefin is treated with an organic sol-vent and then dyed with a coloring agent as described herein, a superior coloring of the polymer is obtained. The color of the polymer obtained is considerably deeper and brighter than that obtained when dyeing polyolefins which contain metal additives but which have not been treated with the solvent or polyolefins which have been treated with the solvent but which do not contain the metal additives.

The organic solvents used in this invention to treat the polyolefin fibers are those solvents in which the polymers are insoluble or dissolve to a maximum of 5% by weight or swell to a maximum of 15% by volume at room temperature. Conventional dry cleaning solvents are particularly effective. Suitable solvents include halogenated saturated or unsaturated hydrocarbons such as carbon tetrachloride, tricholorethylene, perchloroethylene, aromatic hydrocarbons, such as benzene, toluene, xylene, petroleum distillates such as white spirit, mineral spirits, cleaners naphtha, Stoddard solvent, gasoline, etc., aliphatic hydrocarbons such as isooctane, ligroin, cyclohexane, dioxane, etc.

3,424,704 Patented Jan. 28, 1969 The metal compounds which are present and distributed in the polyolefin are compounds of metals having a valence of at least two as disclosed, for example, in Belgian Patent No. 617,280. Preferred metals are aluminum, zinc and nickel. The preferred metal compounds are salts of higher saturated fatty acids and especially those having from 16 to 20 carbon atoms. Especially preferred compounds are aluminum mono-, dior tristearate. The amount of metal compound is preferably between about 0.02 and 0.2% by weight, based on the metal. The metal is distributed uniformly throughout the polymer by a convenient means such as by thorough blending of the metal compound with the polymer at any stage before extrusion of the resin fiber.

The treatment of the metal containing polyolefins may be carried out at room temperature, i.e., about 20 C. and up to about C. The length of time in which the polymer is contacted with the solvent is not critical except that it must be of sufficient time to affect the polymer in order to obtain the desired increase in coloring. Suitable times are bet-ween a few minutes, i.e., about 3 to 5 minutes and up to about an hour. A very short period of time such as 10 to 15 seconds is also unsuitable. Treating times over about one hour are not excluded but in general do not bring about any further increase in polymer colormg.

The polymers which are improved according to the invention are polyolefins and especially the polymers of alpha-monoolefins. Particularly improved is highly crystalline or isotactic polypropylene prepared by the well known low pressure methods in the presence of Ziegler type catalysts. The polymer may be in any suitable form such as fibers, filaments, yarns, fabrics, strips, films, sheets, plates, blocks, rods and the like.

In a particularly preferred embodiment of the invention, following the treatment of the polymers with the solvent the latter is removed as carefully and as thoroughly as possible prior to dyeing or coloring operations. Thus, rather than merely removing solvent, for example, by evaporation at high temperature or by air drying, if the solvent is thoroughly removed by a suitable method, dyeability is improved even to a greater degree. Suitable methods of removing the solvent are, for example, by subjecting the fabrics, fibers, etc. to brushing such as by passing them through one or more brushes or in the case of films, plates, sheets and the like, absorbing the solvent completely on rags, sponges, etc.

Following the removal of the solvent from the polymer the material is colored or dyed according to suitable methods well known to those skilled in the art. The dyes and coloring agents which are improved by the process of this invention are those in which in addition to the coloring groups have a hydroxyl group which is present in the form of a hydroxyl or carboxyl group in an ortho position with respect to a carbonyl group, i.e.,

which is present as a carbonyl group or in the form of a carboxyl group. Examples of suitable dyes of this description are those disclosed in detail in Belgian Patents 617,280, 632,117, 631,326, 632,118 and 632,119. These dyestuffs include azosalicylic acids, diazosalicylic acids, and the corresponding cresotinic acid derivatives and diazorecorsylic acids derived from gamma or beta resorcylic acid. Representative dyestuffs of these types are the following azo dyestufis: 4-acetylbenzeneazosalicylic acid 2,3-dichlorobenzeneazosalicylic acid 4-nitrobenzeneazosalicylic acid 2-trifiuoromethylbenzeneazosalicylic acid 3-trifluoromethylbenzeneazo-o-cresotinic acid 4-fiuorobenzeneazosalicylic acid 3fluorobenzeneazo-m-cresotinic acid Benzeneazobenzeneazosalicylic acid Z-methylbenzeneazo-2-methylbenzeneazosalicylic acid p-Acetophenoneazobenzeneazosalicylic acid 3-chlorobenzeneazobenzeneazosalicylic acid Benzeneazo-gamma-resorcylic acid 3-methylbenzeneazo-gamma-resorcyclic acid Benzeneazo-beta-resorcylic acid 3-methoxybenzeneazo-beta-resorcylic acid Z-chloro--trifluorobenaeneazo-beta-resorcylic acid 4-(pmethoxyphenylamine -benzeneazobeta-resorcylic acid 4-nitrobenzeneazonaphthaleneazo-gamma-resorcylic acid Benzeneazobenzeneazo-beta-resorcylic acid 4-carboxylbenzeneazobenzeneazo-beta-resorcylic acid Other very suitable dyestuifs are those which contain the anthraquinone structure such as described in Belgian Patent 635,938. Examples of suitable anthraquinone type dyes are:

1,2,4-trihydroxyanthraquinone 1,4-dihydroxyanthraquinone 1,2-dihydroxy-3-nitroanthraquinone 4 EXAMPLE III The procedure of Example I was repeated with the omission of the aluminum salt from the polypropylene.

EXAMPLE IV Test samples of polypropylene Were dyed according to Example I without the use of the aluminum salt in the polypropylene and without the solvent treatment.

EXAMPLE V 5 samples and then dyed without further solvent treatment.

The following table shows the comparative results of Examples I-V. In the dyeability results the success of the test is indicated by numerical values from 0-4 as follows:

0no dyeing or only very slightly dyed 1pale, unattractive coloring; unacceptable 2reasona'-ble dyeing, improved color; some samples possessed acceptable coloring 3good dyeing, bright colors; all samples were acceptable in coloring 4 phenylammo 1,5 dihydroxy 8 nitroanthraquinone 1 Xcenent dyeing; all samples had very bright and and the like. deep coloring Solvent treatment Drying Example Sample Additive method Dye Dyeability Solvent Temp., C.

I Fiber 7d aluminum distearate Trichloroethylene 20 A 1,2-hydroxy-3-nitroanthra- 3 (1111110116. I .do do "do B 3 2 A a Trichloroethylene X n 2 Cleaning spirit L. A 3 2 3 4 None 2 Trichloroethylene A 1 do A do 2 Cleaning spirit. A 1,2-hydroxy-3 3 quinone. I ..do do "do 60 B de 4 II do do None do 2 A petroleum fraction having a boiling range between 100 and 130 C.

The following examples illustrate the manner in which the invention is carried out, the components and other details being given in the table below. It is to be understood that the examples are for the purpose of illustration only and the invention is not to be regarded as limited to any specific compounds or conditions set forth therein.

EXAMPLE I Isotactic polypropylene was mixed with an aluminum fatty acid salt to provide a mixture containing 0.08% by weight aluminum. The mixture was extruded to prepare continuous fibers of 7 and 4 denier.

Some of the fibers were converted to yarns by twining. These test samples were then treated with a solvent by immersing the samples in the solvent for a period of 15 to minutes at various temperatures. The samples were then removed from the solvent bath and dried. Two methods were used for drying the samples. According to Method A, the solvent was removed by air drying at from 20 to 100 C. for from 1 to 24 hours with the higher drying temperatures requiring a shorter drying time. By Method B, the solvent was carefully removed from the fibers and yarns by passing through a series of brushes.

All of the samples were then dyed with an aqueous dispersion of 0.06% by weight of d-yestufif and the dyeability determined.

EXAMPLE II The procedure of Example I was repeated with exception that the samples were not treated with a solvent.

From the results obtained, it is clearly evident that the process of the invention of treating the metal containing polypropylene with a suitable solvent gives improved dyeing results as compared to those dyeings where no solvent treatment was used (Examples I and II). On the other hand, the solvent treatment of non-metal containing polymers resulted in poor dyeability. Additionally, the necessity of using the proper sequence during the process is evident (from Example I whereas a diiferent sequence of treatment of the polymer (Example V) resulted in dyeing unimproved over those wherein no solvent was used in treating the fibers (Example II).

I claim as my invention:

1. A process for preparing polyolefins having improved dyeability which comprises treating a fatty acid metal salt containing polyolefin with an organic solvent in which the maximum solubility of the polyolefin is 5% by weight and maximum swelling of the polyolefin is 15% by voltime and wherein the metal is a polyvalent metal and present in the polyolefin in an amount of between about 0.02 and 0.2% by weight and thereafter removing the solvent from the treated polyolefin.

2. The process of claim 1 wherein the metal is an aluminum salt of a saturated fatty acid having from 16 to 20 carbon atoms.

3. The process of claim 1 wherein the solvent is a dry cleaning solvent.

4. The process of claim 1 wherein the solvent is trichloroethylene.

6 5. The process of claim 1 wherein the polyolefin is 3,322,704 5/1967 Berger et a1. 26023 polypropylene. 3,355,402 11/1967 Sasaki et a1. 26023 6. The process of claim 1 wherein the solvent treatment is conducted at a temperature between about 20 and 100 C. for a time between three minutes and one 5 DONALD E. CZAJA, Primary Examiner.

hour' R. A. WHITE, Assistant Examiner.

References Cited UNITED STATES PATENTS 2,984,634 5/1961 Caldwell 6161. 260-23 10 3,257,379 6/1966 May 6161. 260196 26033.6, 33.8, 34.2, 94.9; s -55 

